Thomas C. Booth

At the very start of the pandemic, when performing emergency CTA for patients with suspected stroke, we noticed the presence of ground-glass opacification (GGO) in the apices in those with COVID-19. Additionally, we were aware that the results for Severe Acute Respiratory Syndrome coronavirus 2 (SARS-CoV-2) reverse-transcriptase polymerase chain reaction (RT-PCR) testing were not ready until hours after the CTA, which occurred immediately on admission. If proven, we suspected the presence of GGO would be a simple and “opportunistic” diagnostic biomarker available prior to the PCR results. That had major implications for the management of patients with suspected stroke through early identification of COVID-19 and the limitation of disease transmission.

Therefore, we evaluated the reliability and accuracy of all candidate diagnostic imaging biomarkers. Similarly, we analyzed all the nonimaging “opportunistic” information such as demographics, clinical features, and risk factors for COVID-19 and stroke using univariate and multivariate statistics.

The results show that when the researchers saw these changes in the top of the lungs during the emergency scan, they were able to reliably and accurately diagnose COVID-19, and the changes also predicted increased mortality. This is particularly relevant given the limitations of currently available SARS-CoV-2 RT-PCR testing, as it takes time to complete the test and sometimes it is inaccurate.

The findings can allow earlier selection of the appropriate level of personal protective equipment and attendant staff numbers, triage to appropriate inpatient ward settings, self-isolation, and contact tracing. Additionally, our data have prognostic information given the increased mortality in those with lung changes shown in our cohort.

These are useful results because the changes are simple for radiologists and other doctors to see. This is “free information” from a scan intended for another purpose, yet it is extremely valuable.

The work has been well received, highlighted in news outlets, and spread on social media in Europe and the Americas.

In our hospitals, apical analysis is now articulated in reports to good effect, for example, changing staff personal protective equipment requirements (eg, from a fluid-repellent surgical mask to an FFP3 or N95 mask) and directing a patient to a side room instead of an open ward, pending RT-PCR results.

We have presented the findings at national meetings, and we hope this has helped with a safer patient pathway.

We used other information readily available at the time of the carotid CTA acquisition but were unable to find any other additional biomarkers. This included demographics, clinical history, symptoms and signs, as well as chest radiographs (which are typically obtained shortly after the admission of patients with acute stroke). We analyzed the chest radiographs and showed that chest radiograph assessment should not, therefore, replace a simple assessment of the presence of ground-glass opacification on CTA for COVID-19.*

While this study was based in London, United Kingdom, and included 3 hospitals with a multiracial population ranging from 10% to 40% and including patients whose socioeconomic status varied in the catchment area, we believe the biomarker would benefit from further rigorous temporal and spatial validation. In other words, having developed the biomarker, we should now test it on a cohort of patients from hospitals throughout an entire nation with prospective data collection at a subsequent time point in the pandemic. Such a study to obtain highly representative samples of the populations with acute stroke during the COVID-19 pandemic is currently underway. There is a supernetwork of enthusiastic, young UK neuroradiologists who have collaborated to make this happen, led by Dr. Tarini Ratneswarwen and Dr. Nathan Chan.**

The results of the prospective multicenter study will be published this year and presented at national and international radiology and stroke meetings.

*Also published in AJNR: Siddiqui J, Bala F, Sciacca S, et al. A comparison of chest radiograph and CTA apical pulmonary findings in patients presenting with suspected acute stroke during the COVID-19 pandemic. AJNR Am J Neuroradiol 2021;42:E13–14

**King’s College Hospital National Health Service Trust. COVID-19 Stroke Apical Lung Examination Study - A Multi-Centre Prospective Study. ClinicalTrials.gov; 2021. https://clinicaltrials.gov/ct2/show/NCT04640428. Accessed March 24, 2021.

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